Mobile Communication System

1. A mobile communication system comprising: a first mobile station; a second mobile station; a radio base station; a first radio base station interface between the first mobile station and the radio base station; a second radio base station interface between the second mobile station and the radio base station; and an inter-mobile station interface between the first mobile station and the second mobile station, wherein the radio base station transmits a data signal to the first mobile station and the second mobile station through the first and second radio base station interfaces at a first frequency, the first mobile station and the second mobile station transmit the data signal to the radio base station through the first and second radio base station interfaces at a second frequency, the first mobile station and the second mobile station transmit and receive the data signal to and from each other through the inter-mobile station interface at the second frequency, the transmission of the data signal through the first and second radio base station interfaces at the second frequency and the transmission and reception of the data signal through the inter-mobile station interface at the second frequency are performed in a time-division manner, and predetermined gaps are provided before and after timing in which the first mobile station and the second mobile station transmit the data signal through the inter-mobile station interface, in consideration of a time required to switch between the transmission of the data signal through one of the first and second radio base station interfaces and the inter-mobile station interface and the reception of the data signal through the inter-mobile station interface in the second frequency.

2. The mobile communication system according to claim 1 , wherein duration of the predetermined gap or duration of a subframe except the predetermined gap is specified in units of symbols.

3. The mobile communication system according to claim 1 , wherein the radio base station notifies the first mobile station and the second mobile station of duration of the predetermined gap.

4. A mobile communication system comprising: a first mobile station; a second mobile station; a radio base station; a first radio base station interface between the first mobile station and the radio base station; a second radio base station interface between the second mobile station and the radio base station; and an inter-mobile station interface between the first mobile station and the second mobile station, wherein the radio base station transmits a data signal to the first mobile station and the second mobile station through the first and second radio base station interfaces at a first frequency, the first mobile station and the second mobile station transmit and receive the data signal to and from each other through the inter-mobile station interface at the first frequency, the first mobile station and the second mobile station transmit the data signal to the radio base station through the first and second radio base station interfaces at a second frequency, the transmission of the data signal through the first and second radio base station interfaces at the first frequency and the transmission and reception of the data signal through the inter-mobile station interface at the first frequency are performed in a time-division manner, and predetermined gaps are provided before and after timing in which the first mobile station and the second mobile station transmit the data signal through the inter-mobile station interface, in consideration of a time required to switch between the reception of the data signal through one of the first and second radio base station interfaces and the inter-mobile station interface and the transmission of the data signal through the inter-mobile station interface in the first frequency.

5. The mobile communication system according to claim 4 , wherein duration of the predetermined gap or duration of a subframe except the predetermined gap is specified in units of symbols.

6. The mobile communication system according to claim 4 , wherein the radio base station notifies the first mobile station and the second mobile station of duration of the predetermined gap.

7. A mobile communication system comprising: a first mobile station; a second mobile station; a radio base station; a first radio base station interface between the first mobile station and the radio base station; a second radio base station interface between the second mobile station and the radio base station; and an inter-mobile station interface between the first mobile station and the second mobile station, wherein the radio base station transmits a data signal to the first mobile station and the second mobile station through the first and second radio base station interfaces at a first frequency, the first mobile station and the second mobile station transmit the data signal to the radio base station through the first and second radio base station interfaces at a second frequency, the first mobile station and the second mobile station transmit and receive the data signal to and from each other in a time-division manner through the inter-mobile station interface at a third frequency, and predetermined gaps are provided before and after timing in which the first mobile station and the second mobile station transmit the data signal through the inter-mobile station interface, in consideration of a time required to switch between transmission of the data signal through the inter-mobile station interface and reception of the data signal through the inter-mobile station interface in the third frequency.

8. The mobile communication system according to claim 7 , wherein duration of the predetermined gap or duration of a subframe except the predetermined gap is specified in units of symbols.

9. The mobile communication system according to claim 7 , wherein the radio base station notifies the first mobile station and the second mobile station of duration of the predetermined gap.